Mandarin plant named &#39;Merbeingold 2336&#39;

ABSTRACT

‘Merbeingold 2336’ is a new Australian variety of mandarin. It was selected from the progeny obtained following a controlled pollination of ‘Imperial’ mandarin×‘Ellendale’ tangor in 1984. It was selected because it is pollen sterile, strongly parthenocarpic and yields seedless fruits, which are sweet, juicy and easy-to-peel. Fruit maturity is early-to-mid season in the Murray Valley of Australia. Internally, the flesh of ‘Merbeingold 2336’ is attractive, orange in colour and tender with soft segment walls.

This application is a continuation of U.S. plant application Ser. No.11/729,003, filed Mar. 27, 2007, claiming priority of AustralianBreeder's Right Application No. 2006/278, filed Oct. 16, 2006 thecontents of all of which are hereby incorporated by reference.

‘Merbeingold 2336’ was accepted for Plant Breeder's Right (“PBR”)registration on Dec. 1, 2006 when a provisional PBR was granted.Acceptance was published in the Plant Varieties Journal (2007) Vol. 19,No 4, p23 (see, ipaustralia.gov.au/pdfs/plantbreed/PVJ_(—)19_(—)4.pdf).The Commonwealth of Australia Plant Breeder's Rights Act 1994 followsthe guidelines of the International Convention for the Protection of NewVarieties of Plants—UPOV Convention (1961), as revised at Geneva (1972,1978 and 1991). Australia is a UPOV Member State.

LATIN NAME OF THE GENUS AND SPECIES OF THE PLANT CLAIMED

Citrus reticulata×(C. reticulata×C. sinensis)

VARIETY DENOMINATION

‘Merbeingold 2336’

BACKGROUND OF THE INVENTION

‘Merbeingold 2336’ is a new variety of mandarin (Citrus species) bred byCSIRO Plant Industry. A copending application, U.S. Ser. No. 11/729,049,has been made for the variety ‘Merbeingold 2350’, which is a siblingselected from the same family as ‘Merbeingold 2336’.

‘Merbeingold 2336’ is a mandarin variety selected from a family producedby making a controlled cross between ‘Imperial’ mandarin (seed parent)with ‘Ellendale’ tangor (pollen parent). Thus, the botanical name forthe plant is:

Citrus reticulata×(C. reticulata×C. sinensis)

The plant may be used for horticultural production of mandarin fruits.

‘Merbeingold 2336’ was selected from a family of 241 hybrids generatedby a controlled cross-pollination of ‘Imperial’ mandarin (maternalparent) with ‘Ellendale’ tangor (pollen parent).

‘Imperial’ mandarin (unpatented) is an Australian variety thatoriginated at Emu Plains, NSW., as a chance seedling in 1890. It ispossibly a hybrid of the ‘Mediterranean’ mandarin. ‘Imperial’ trees arevigorous, upright and of medium size and they yield fruits that areearly maturing.

‘Ellendale’ tangor (unpatented) is another Australian variety that wasdiscovered as a chance seedling at Burrum, Queensland in 1878. Althoughits parentage is unknown, its characteristics and fruit size indicatethat it is a tangor (mandarin×orange cross). ‘Ellendale’ trees aregenerally large and of a spreading-round habit and produce largemid-to-late season fruit depending on where they are grown.

The seediness of fruits from both ‘Imperial’ and ‘Ellendale’ can bevariable ranging from many-to-few-to-zero depending on the proximity ofother sources of pollen. Both varieties are capable of producing fruitsparthenocarpically.

CSIRO Plant Industry crossed ‘Imperial’ with ‘Ellendale’ to combine thecharacteristics of the two varieties and generate new parthenocarpichybrids for selection of potential new varieties of seedless mandarins.

The controlled cross-pollination was conducted by emasculating anun-opened flower bud of the maternal parent and applying pollen from thepaternal parent to the receptive stigma using a sterile soft-hairedpaintbrush. Pollen of ‘Ellendale’ tangor was collected by dryinganthers, which had been removed from unopened flower buds, in Petridishes over silica gel in a dessicator. Dried dehisced anthers werestored in sealed glass vials over silica gel at 4° C. until needed. Thecross was made in 1984 and the resultant seeds were extracted fromfruits in 1985 and sown in a standard seed bed under glasshouseconditions. Emergent seedlings were transferred to a standard pottingmix in pots and maintained under glasshouse conditions until they wererowed out in the breeding orchard at a planting density of 2 m withinand 6 m between rows. Hybrid seedlings were maintained under irrigatedorchard conditions thereafter. Standard citrus cultivation techniqueswere used to maintain the trees including application of fertilisers.

When hybrid 2336 flowered, it was subjected to a range of pollinationtreatments to assess its potential for producing seedless fruits. Fruitswere harvested over 4 years and assessed for fruit quality, Based on thedata collected, hybrid 2336 was selected for entry into second phaseevaluation trials.

The selection was entered into a comparative trial at CSIRO PlantIndustry Koorlong (NW. Victoria). Trees of hybrid 2336 and 4 comparatorvarieties (viz. ‘Clementine Nules’, ‘Imperial’ mandarin, ‘Ellendale’tangor, and ‘Merbeingold 2350’) were propagated by budding to 3rootstocks (viz. ‘Carrizo’ citrange, ‘Cleopatra’ mandarin and ‘Symons’sweet orange) in the nursery at CSIRO. The DUS trial was planted duringspring 2001. The soil type was classified as being Tiltao sand(Northcote, K.H. 1951. A Pedological Study of the Soils Occurring atCoomealla, New South Wales, Commonwealth Scientific and IndustrialResearch Organisation, Melbourne, Australia). The trees were irrigatedby overhead sprays and fertilised using a standard citrus N:P:K (12:3:3)formulation. Fertiliser was applied to young trees at 2-monthlyintervals and to trees 2 years and older at six-monthly intervals at arate such that they received 800 kg/ha/year. Trace elements, primarilymanganese and zinc were applied as foliar sprays as required. The trialwas embedded within a larger trial that compared other selections fromCSIRO's citrus breeding program. The trial was laid out as tworandomized blocks with a three-tree plot for every scion/rootstockcombination within each block. Rootstocks were randomized within plots.Trees were maintained vegetatively for the first three years and allowedto retain fruits from season 2004-05 onwards.

Comparative data for quantitative fruit characteristics were collectedin seasons 2006 and 2007. Spring-flush leaves were sampled from treesduring January 2007.

Hybrid 2336 was also entered along with other selections into regionaltest plots with anonymous cooperating citrus growers under confidentialtesting agreement arrangements to protect inherent intellectualproperty. Based on its performance in these trials and test plots,hybrid 2336 was named ‘Merbeingold 2336’.

Daughter trees of ‘Merbeingold 2336’ propagated from the originalseedling tree by asexual or vegetative means are uniform and stable.Similarly grand-daughter trees are uniform and stable. Trees of‘Merbeingold 2336’ have been propagated by grafting or budding toseedling rootstocks, by top-working to established orchard trees and byrooting cuttings, confirming its uniformity and stability.

BRIEF SUMMARY OF THE INVENTION

Fruits of ‘Merbeingold 2336’ are seedless even when challenged by viablepollen in an open-pollinated situation. The fruits are easy-to-peel andupon peeling, the segments are readily separated although some albedotissue may adhere to the segments. Peeled segments are very tender withrelatively soft walls meaning they are easy to consume and as a resultthe fruit has been described as melting. The juice has a ° Brix ofaround 10 and an acid concentration of less than 1% at maturity, whichgives a sweet flavour. The flavour and soft, easy-eating texture of thesegments are favoured by children.

Though more orange than red-orange, the colour of the rind is moreintense than ‘Imperial’ mandarin. Like ‘Imperial’ mandarin, rindstrength is not high, which suggests the fruit may be more suited fordomestic sales rather than shipping to more distant export markets.

Large fruits tend to be puffy, although cultural practices such as GAsprays have a positive effect to reduce this and improve rind quality.Fruits of ‘Merbeingold 2336’ can be snapped from the tree, but careshould be taken as the button will be removed if harvesting is tooviolent. Fruits of ‘Merbeingold 2336’ are mature in the periodJune-through-July in Australia's Murray Valley, although the exact timefor optimum quality will depend on rootstock and season. The range infruit size tends to be similar to that of ‘Imperial’ mandarin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C: Show leaves from ‘Merbeingold 2336’ (FIG. 1A) and itsparents, ‘Imperial’ mandarin (FIG. 1B) and ‘Ellendale’ tangor (FIG. 1C).In ‘Merbeingold 2336’ the Lamina length:width ratio=2.2±0.3; in‘Imperial’ mandarin the Lamina length:width ratio=2.7±0.2; and in‘Ellendale’ tangor the Lamina length:width ratio=2.1±0.2

FIGS. 2A-2C: Show fruit of ‘Merbeingold 2336’ (FIG. 2A) and its parents,‘Imperial’ mandarin (FIG. 2B) and ‘Ellendale’ tangor (FIG. 2C).

DETAILED BOTANICAL DESCRIPTION

Variety—‘Merbeingold 2336’

Citrus reticulata×(C. reticulata×C. sinensis)

Descriptors used herein from 1) European Union Community Plant VarietyOffice, Protocol for distinctness, uniformity and stability tests.Citrus L.—Group 1 MANDARINS. CPVO-TP\201\1 Adopted 18 Nov. 2004, and 2)IPGRI (1999) Descriptors for Citrus. International Plant GeneticResources Institute, Rome, Italy (ISBN 92-9043-425-2).

-   Plant: Diploid, growth habit spreading-to-upright, tree shape    spheroid, density of branches medium, branch angle narrow, trunk    surface smooth, shoot tip green and surface glabrous.-   Spine (thorn): Absent on adult tree.-   Leaf: Evergreen, type simple, shape ovate, intensity of green colour    on lamina medium-to-dark, colour variegation absent, margin weakly    dentate, shape of apex acute, length medium (91±11 mm), lamina width    broad (42±6 mm), lamina length to width ratio 2.2±0.3,    cross-sectional shape intermediate, lamina undulation slight, lamina    attachment brevipetiolate, petiole length short (10±3), petiole    wings obdeltate and very narrow, petiole attachment to stem curved,    junction between petiole and lamina articulate, colour of    upper/lower surface of lamina same.-   Flower: Hermaphrodite, arrangement solitary and as a raceme,    position axillary and terminal, length of petal medium, anther    colour pale yellow-to-white, viable pollen absent, length of anther    relative to style shorter (inferior), colour of open flower white, 5    petals per flower, stamens >4 per petal, style straight and    complete, self-pollen reaction sterile.-   Fruit: Maturity early-to-mid-season (June Australia), borne both    inside and outside canopy, obloid, attachment to stalk    medium-to-strong, broadest at equator, shape in transverse section    circular, base truncate, apex depressed slightly, neck absent,    slight depression at stalk end, number of radial grooves at stalk    end intermediate, collar absent, distal part slightly    concave-to-flattened, depression at distal end, areola absent,    stylar end closed, stylar scar small, style not persistent, navel    opening absent, radial grooves at distal end absent, rind surface    orange, surface glossiness strong, rind surface smooth-to-very    slightly pitted, oil glands all more-or-less same size, slight    pitting of oil glands present pebbling absent, oil glands very    weakly conspicuous, small and of low density, rind thickness medium    (3-5 mm), rind adherence to flesh weak, rind strength medium, rind    oiliness dry, albedo white and loose, amount of albedo adhering to    flesh small-to-medium, albedo strands present, flesh medium orange,    pulp colour uniform, pulp firmness soft, pulp texture fleshy, core    medium, round and sparsely filled, segments uniform, rudimentary    segments absent, number of well developed segments medium (7-12;    mean 9.5±1.7), adherence of segment walls to each other medium,    segment walls thin and weak, vesicle length medium, vesicle    thickness medium, navel absent, juiciness medium-to-high, total    soluble solids medium 9-11 ° Brix, juice acidity low-to-medium,    strength of fibre weak, parthenocarpy present.-   Seed: Number zero under controlled manual self pollination, or 0-3    (mostly 0) under open-pollination dependent on proximity of pollen    sources, monoembryonic, shape ovoid, length short, width narrow,    surface smooth, external colour whitish/cream, colour of inner seed    coat light brown, chalazal cream, cotyledons white-to-light    yellow-cream.

1. A new and distinct pollen sterile, parthenocarpic mandarin varietynamed ‘Merbeingold 2336’ as illustrated and described.